Spotting Earth-threatening asteroids
is tough partly because the sky is so big. But insects offer an answer,
since they figured out long ago how to look in many directions at once.
As part of the global effort to hunt out risky celestial objects such
as asteroids and comets, ESA is developing an automated telescope for
nightly sky surveys. 1)

This telescope is the first in a
future network that would completely scan the sky and automatically
identify possible new near-Earth objects, or NEOs, for follow up and
later checking by human researchers. But a web of traditional
telescopes would be complex and expensive because of the number
required. Adding to the problem, the system must be able to discover
objects many times fainter than the naked eye can perceive.

While no network can spot all
potentially hazardous objects, under favorable conditions it should
detect everything down to about 40 m in diameter at least three weeks
before impact.

The answer is a new, European telescope nicknamed ‘Flyeye’
that splits the image into 16 smaller subimages to expand the field of
view, similar to the technique exploited by a fly’s compound eye.

The design is modular, and allows
for mass and cheaper production and lower maintenance costs. It will be
used to build the prototype, to be fielded by ESA’s Space
Situational Awareness (SSA) program. “This novel technology is
key to the future NEO survey network,” says Gian Maria Pinna of
the SSA office.

Performance equivalent to large telescope

In the telescope, a single mirror of
1 m equivalent aperture collects the light from the entire 6.7º x
6.7º field of view [about 45 square degrees; 6.7º is about 13
times the diameter of the Moon as seen from the Earth (roughly
0.5º)] and feeds a pyramid-shaped beam splitter with 16 facets.
The complete field of view is then imaged by 16 separate cameras. The
red caps in the image are the covers over the 16 cameras that contain
the 16 detectors. The tubes contain a set of secondary lenses.

“The new telescopes would
provide the resolution necessary to determine the orbits of any
detected objects,” says Gian Maria. “If the prototype
confirms the expected performance, it will pave the way to full
procurement and deployment of the operational network of
telescopes.”

In the summer of 2014, ESA signed a
contract for about €1 million with a consortium led by CGS S.p.A
(Italy), comprising Creotech Instruments S.A. (Poland), SC EnviroScopY
SRL (Romania) and Pro Optica S.A. (Romania) for the detailed design of
the advanced telescope. 2)

It is expected that the detailed
design will be followed by several additional contracts with European
companies valued at up to €10 million for building and deploying
the first survey prototype telescope.

“The development of the first
optical sensor specific to ESA’s NEO search and discovery
activities is a fundamental step toward Europe’s contribution to
safeguarding our planet from possible collisions by dangerous
objects,” notes Nicolas Bobrinsky, Head of the SSA Program.

The first Flyeye telescope is
expected to be ready for installation at its final location on Mount
Mufara in Sicily at the end of 2019.

ESA’s
automated Flyeye telescope will help Europe discover risky celestial
objects such as asteroids and comets during its nightly sky surveys. It
will automatically identify possible new near-Earth objects for follow
up and later checking by human researchers as part of Europe’s
SSA (Space Situational Awareness) Program. 5)

Figure 4:
The equatorial mount that will hold the Flyeye telescope orients the
direction of view around the right ascension and the declination axis
– the celestial coordinates. By doing so, it compensates for the
rotation of the Earth by movement of one axis only and avoids image
rotation during exposures (image credit: OHB Italia)

Legend to Figure 4:
The black structure at the center of the mount in this picture is for
testing purposes and will be replaced with the Flyeye telescope. The
mount and telescope are now being integrated in Milan, Italy, by OHB
Italia ready for installation at the final location on Mount Mufara in
Sicily at the end of 2019.

Figure 5: The
Flyeye telescope infographic illustrates how ESA will use first-ever
‘flyeye’ telescopes to support the UN and international
efforts to respond to asteroid risks (ESA) 6)

ESA is developing new
‘flyeye’ telescopes to conduct automated nightly sky
surveys. Up to four Flyeye Telescopes will be located worldwide.
Together with sightings from European and international astronomers,
Flyeye data will be sent to the IAU (International Astronomical Union) Minor Planet Center (USA), the world’s central clearing house for all asteroid sightings.

ESA asteroid experts work with other
space agencies and European civil protection authorities to devise
mitigation measures. ESA also supports asteroid warning and risk
assessment activities at the United Nations, in cooperation with
experts from the IAU and worldwide.

Asteroid Impact Exercise

• 19 June 2019: ESA will be participating in this year’s Asteroid Day,
the UN-endorsed global awareness campaign day on the small rocky bodies
scattered across space, taking place on Sunday, 30 June. 7)

- The Agency will share with media and public its various activities
related to asteroids, which it regards as a vital subject for
scientific study, as ‘time capsules’ from early in the
history of the Solar System and the birth of the planets.

-
Asteroids have influenced Earth’s development, as seen by the
millions of impact craters scarring our world. They are also a
promising source of future resources and – last but not least
– they pose a proven threat to Earth and human civilization. ESA
is taking action as part of an international effort to mitigate this
risk.

- Over the last two decades, ESA has
been performing detection and analysis of asteroids whose orbits bring
them close to Earth, known as near-Earth objects (NEOs). There are an
estimated 10,000,000 NEOs out there larger than 10 m – the
threshold above which damage on the ground could happen.

- As part of its space safety activities, ESA coordinates observatories and astronomers worldwide through its NEO Coordination Center, located at ESA’s ESRIN facility in Italy.

- Building on this experience, ESA has developed a new type of automated telescope for nightly sky surveys. This ‘Flyeye’ telescope
splits its image into 16 smaller subimages to expand the field of view,
similar to the technique exploited by a fly’s compound eye.

- A network of these Flyeye
telescopes would completely scan the sky and automatically identify
possible NEOs for follow up and later checking by human researchers.

- The first Flyeye telescope is
being installed atop the 1865-m Monte Mufara mountain in Sicily; the
same island where the very first asteroid was discovered back in 1801.

- A network of Flyeye telescopes is
being proposed for approval by Europe’s space ministers at
Space19+ this November as part of ESA’s Space Safety initiative.

• 29 April 2019: In a
fictional dramatization, ESA has been monitoring an asteroid en route
to strike Earth, although a crucial piece of information - where it
might hit - is not yet clear. It’s the
year 2028, and the European Space Agency has been carefully monitoring
a worrying situation: an enormous asteroid is en route to strike Earth,
although the exact point of impact is not yet clear. 8)

- National governments are planning
to evacuate millions of people, an undertaking that will cause untold
human misery and disruption on a gigantic scale. If the
asteroid’s impact zone can be fixed, perhaps such chaos can be
avoided.

- As precious hours pass, find out
how ESA’s Planetary Defence Office is able to obtain crucial
information on this potential disaster as part of the Agency’s
Space Safety activities.

• 26 April
2019: For the first time, ESA will cover a major international asteroid
impact exercise live via social media, highlighting the the actions
that might be taken by scientists, space agencies and civil protection
organizations. 9)

- Every two years, asteroid experts
from across the globe come together to simulate a fictional but
plausible imminent asteroid impact on Earth. During the week-long
scenario, participants – playing roles such as ‘national
government’, ‘space agency’, ‘astronomer’
and ‘civil protection office’ – don't know how the
situation will evolve from one day to the next, and must make plans
based on the daily updates they are given.

- For the first time, ESA will cover
progress of the hypothetical impact scenario from 29 April to 3 May
live via social media, primarily via the @esaoperations Twitter
channel.

- The exercise is being produced by experts from NASA's Planetary Defence Coordination Office working together with the US Federal Emergency Management Agency at the 2019 Planetary Defense Conference,
Washington DC. The conference is the world’s most important
gathering of asteroid experts, and is strongly supported by ESA, NASA
and other agencies, organizations and scientific institutions.

- “Only then, with enough
warning, can we take the steps needed to prevent an asteroid strike
altogether, or to minimize the damage it does on the ground.”

20,000 asteroid milestone

- As of April 2019, 20,000 asteroids
whose orbit brings them near Earth have been found. At the current rate
of roughly 150 new discoveries every month, this number is set to
rapidly increase.

- With the planned deployments of ESA’s new Flyeye
and Test-Bed Telescopes, Europe’s ability to discover, confirm
and understand the ancient rocks that hurtle through space will grow
– fundamental to implementing mitigation measures.

Figure 7: Visualization of
asteroid Itokawa. This artist’s impression, based on detailed
spacecraft observations, shows the strange peanut-shaped asteroid
Itokawa. By making exquisitely precise timing measurements using
ESO’s New Technology Telescope a team of astronomers has found
that different parts of this asteroid have different densities. As well
as revealing secrets about the asteroid’s formation, finding out
what lies below the surface of asteroids may also shed light on what
happens when bodies collide in the Solar System, and provide clues
about how planets form [video credit: JAXA, ESO/L. Calçada/M.
Kornmesser/Nick Risinger (skysurvey.org),Published on 26 April 2017]

Follow asteroid impact exercise live

- The @esaoperations
Twitter channel will share updates on the asteroid impact exercise in
realtime, including daily press releases revealing how the asteroid
impact scenario will evolve, so followers will find out the
‘news’ as the experts do.

Figure 8:
Estimated risk corridor for the impact of a hypothetical asteroid. The
graphic is showing the hypothetical impact risk corridor of asteroid
2019 PDC (Planetary Defense Conference), when its orbit is still not
fully known (image credit: 2019 PDC Exercise)

Legend to Figure 8:
The asteroid’s uncertainty region at the time of the potential
impact is much longer than the diameter of the Earth, but its width is
only about 70 km (45 miles). The intersection of the uncertainty region
with the Earth creates a so-called “risk corridor” across
the surface of the Earth. The corridor wraps more than halfway around
the globe, spanning from the Hawaii on the western end, across the US
and Atlantic Ocean, and all the way to central and southern Africa on
the eastern end. The red dots on the Google Earth image trace the risk
corridor.

On ESA Facebook,
join us for two live-stream videos straight from the Planetary Defense
Conference. The first will be on Sunday, 28 April, at 14:00 CEST (08:00
EDT) with Rüdiger Jehn, ESA’s Head of Planetary Defence, and
the second on Thursday, 2 May, at around mid-afternoon European time.

For daily updates on the asteroid
impact scenario, check out “Rolling coverage: Brace for
hypothetical asteroid impact”, beginning on the first day of the
conference, Monday, 29 April, over on ESA's Rocket Science blog.

Asteroid 2019 PDC hypothetical impact scenario: The
scene has been set for this year’s hypothetical impact scenario.
Although realistic, it is completely fictional and does not describe an
actual asteroid impact.

• An asteroid was discovered on 26 March 2019 and was given the name '2019 PDC' by the Minor Planet Center.

• Very
little is known about this newly discovered asteroid’s physical
properties. With a magnitude (brightness) of 21.1 – invisible to
the naked eye but viewable by professional astronomers – it has
been classed as a ‘Potentially Hazardous Asteroid’, and
experts have determined its average size could be anywhere from 100-300
meters.

• The day after 2019 PDC was
discovered, ESA and NASA’s ‘impact monitoring
systems’ identified several future dates when the asteroid could
hit Earth. At this early stage, with not many observations yet
recorded, both systems agreed that the asteroid was most likely to
strike on 29 April 2027 – more than eight years away – with
a probability of impact of about 1 in 50,000.

• Astronomers continued to
monitor the asteroid for a month after its initial detection, which
provided them more information about the object’s trajectory, and
have now discovered that the chance of impact is rapidly increasing. By 29 April 2019, (the first day of the Planetary Defence Conference), the probability of impact has risen to 1 in 100.

ESA coordinates European efforts

The 2019 Planetary Defence
Conference will be the sixth such conference that the International
Academy of Astronautics (IAA) has held; and ESA has been closely
involved with all of them.

During the hypothetical asteroid
impact scenario, ESA experts will participate in discussions on the
possible risks posed by asteroid 2019 PDC, and what responses could be
considered.

“Fortunately, impacts from
medium and large asteroids are not very common,” explains Detlef
Koschny, senior asteroid expert at ESA who will be involved in the
hypothetical scenario.”

“However, this means we have
little opportunity to practise our response to this very real –
though unlikely – danger. This year’s impact scenario is a
very unique chance to run through, in real-time, an asteroid
impact.”

Solar activity, asteroids and artificial space debris all pose threats to our planet and our use of space.

SA's Space Safety activities aim to
safeguard society and the critical satellites on which we depend,
identifying and mitigating threats from space through projects such as
the Flyeye telescopes, the Lagrange space weather mission and the Hera
asteroid mission.

As asteroid experts meet for the
international Planetary Defense Conference, ESA is focusing on the
threat we face from space rocks. How likely is an asteroid impact? What
is ESA doing to mitigate impact risks? Follow the hashtag #PlanetaryDefense to find out more.

Figure 10: As we discover more
about the brilliant scale and nature of the Universe, planet
Earth’s blue oceans, green forests and glistening city lights
appear even more unique, and even more fragile. Many hazards have been
identified originating in space, which although unlikely, continue to
pose real dangers to our way of life, and in the worst cases to human
health and safety. Only in the past decades have we had the opportunity
to understand the potential perils of our position in our Solar System,
and as technologies continue to advance we are entering a period in
which we can actually act. However, as technologies advance, so too
does our dependence on them, making us more vulnerable to both
human-made and natural threats in space. Find out more about ESA's
space safety and security activities, here (image credit: ESA)

The information compiled and edited in this article was provided byHerbert
J. Kramer from his documentation of: ”Observation of the Earth
and Its Environment: Survey of Missions and Sensors” (Springer
Verlag) as well as many other sources after the publication of the 4th
edition in 2002. - Comments and corrections to this article are always
welcome for further updates (herb.kramer@gmx.net).